The present invention relates to a track assembly having a track trained in endless fashion to circumscribe a supporting framework including a drive sprocket and a plurality of idler wheels mounted to the framework to prevent “caterpillaring” (i.e. flexing of the track in spaces between seriatim mounted idler/road wheels).
Track supported vehicles and equipment are designed for a variety of applications. The tracks enhance traction, distribute vehicle weight and reduce loading over an enlarged ground contact surface versus wheels and tires. Track systems of various designs are commonly used with military, commercial, farm, construction, personal (e.g. truck) and sport/leisure (e.g. snowmobiles and ATV) vehicles. Tracks are also used in a variety of other applications with passive, un-powered equipment, for example, trailers, irrigation equipment and the like.
Depending upon the application, the track support framework and/or mounting system desirably provides some freedom of movement at the track assembly to flex and otherwise compensate for dynamically changing terrain conditions and/or to enhance operating performance and/or track retention. Typically, the framework is mounted to pivot as obstructions are encountered and passed over. A track assembly of applicant that provides torsion control to prevent contact between a track assembly and a supporting vehicle is shown at U.S. Pat. No. 5,607,210. Other track assemblies developed by applicant are shown at U.S. Pat. Nos. 6,904,986; 6,926,105; 7,533,741 and 8,083,242.
The foregoing track assemblies generally provide for left and right, symmetrically arranged idler or road wheels that are longitudinally aligned in seriatim fashion along the bottom of the track to support a rubber, belted track. Longitudinal gaps are thereby defined between the leading and lagging idler wheels that can reduce a track's operating efficiency and even exaggerate track wear. That is, a flexing, lifting or buckling of the track can occur in the space between the seriatim idler wheels. The flexion arises from a normal degree of slack in the track tension during track rotation as rocks, logs, pothole edges and other contour variations are encountered in the terrain.
The flexing or buckling of the track reduces the contact surface area of the track with the terrain which lessens the track support and increases the contact pressure at the track footprint. The buckling or flexion can also induce fatigue in the cording of a rubber track and lessen the operating life of the track. Under some circumstances the track can also dislodge from the track assembly and support framework.
The present invention was developed to provide a track assembly and support framework wherein a plurality of secondary track support idler wheels are mounted in a staggered arrangement at the bottom drive surface of the track relative to normally provided primary right and left arrangements of seriatim idler wheel. The staggered secondary idler wheels prevent buckling or caterpillaring of the track in the spaces between the primary idler wheels.
One arrangement provides a track support framework having a first set of primary or outer idler wheels longitudinally mounted in generally conventional seriatim fashion that rotate parallel to and adjacent the lateral peripheral edges of the track. A secondary set of idler wheels are mounted interiorly of the primary outer idler wheels and contact the drive surface of the track in longitudinal regions between the outer wheels. The interior wheels are located to stabilize the track in the intermediate spaces between the primary idler wheels and prevent flexing and/or buckling of the track in the longitudinal spaces between the seriatim outer wheels.